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1.
Binaural and frequency representation in the primary auditory cortex of the big brown bat, Eptesicus fuscus 总被引:3,自引:0,他引:3
J. X. Shen Q. C. Chen P. H.-S. Jen 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(6):591-597
This study examines the binaural and frequency representation in the primary auditory cortex (AC) of the big brown bat, Eptesicus fuscus, by using an ear-phone stimulation system. All 306 cortical neurons studied were excited by contralateral sound stimulation
but they were either excited, inhibited or not affected by ipsilateral sound stimulation. These cortical neurons were columnarly
organized according to their binaural and frequency-tuning properties. The excitation-excitation columns which occupy about
15% of the AC are mainly aggregated within an oval-shaped area of the central AC. The excitation-inhibition neurons and binaural
neurons with mixed properties are distributed in the remaining 85% of the surrounding primary AC. Although the best frequency
(BF) of these neurons shows a tendency to decrease from high to low along the anteroposterior axis of the primary AC, systematic
variation in BF is not always consistent across the entire mapping area. In particular, BFs of cortical neurons isolated in
the anterior AC vary quite unsystematically such that neurons with similar BFs are aggregated in isolated patches. Isofrequency
and binaural columns are segregated into bands that intersect each other.
Accepted: 13 August 1997 相似文献
2.
How do neuronal populations in the auditory cortex represent acoustic stimuli? Although sound-evoked neural responses in the anesthetized auditory cortex are mainly transient, recent experiments in the unanesthetized preparation have emphasized subpopulations with other response properties. To quantify the relative contributions of these different subpopulations in the awake preparation, we have estimated the representation of sounds across the neuronal population using a representative ensemble of stimuli. We used cell-attached recording with a glass electrode, a method for which single-unit isolation does not depend on neuronal activity, to quantify the fraction of neurons engaged by acoustic stimuli (tones, frequency modulated sweeps, white-noise bursts, and natural stimuli) in the primary auditory cortex of awake head-fixed rats. We find that the population response is sparse, with stimuli typically eliciting high firing rates (>20 spikes/second) in less than 5% of neurons at any instant. Some neurons had very low spontaneous firing rates (<0.01 spikes/second). At the other extreme, some neurons had driven rates in excess of 50 spikes/second. Interestingly, the overall population response was well described by a lognormal distribution, rather than the exponential distribution that is often reported. Our results represent, to our knowledge, the first quantitative evidence for sparse representations of sounds in the unanesthetized auditory cortex. Our results are compatible with a model in which most neurons are silent much of the time, and in which representations are composed of small dynamic subsets of highly active neurons. 相似文献
3.
Categorical perception is a process by which a continuous stimulus space is partitioned to represent discrete sensory events.
Early experience has been shown to shape categorical perception and enlarge cortical representations of experienced stimuli
in the sensory cortex. The present study examines the hypothesis that enlargement in cortical stimulus representations is
a mechanism of categorical perception. Perceptual discrimination and identification behaviors were analyzed in model auditory
cortices that incorporated sound exposure-induced plasticity effects. The model auditory cortex with over-representations
of specific stimuli exhibited categorical perception behaviors for those specific stimuli. These results indicate that enlarged
stimulus representations in the sensory cortex may be a mechanism for categorical perceptual learning. 相似文献
4.
《Neuron》2023,111(13):2105-2118.e4
5.
Degraded auditory processing in a rat model of autism limits the speech representation in non‐primary auditory cortex 下载免费PDF全文
C.T. Engineer T.M. Centanni K.W. Im M.S. Borland N.A. Moreno R.S. Carraway L.G. Wilson M.P. Kilgard 《Developmental neurobiology》2014,74(10):972-986
Although individuals with autism are known to have significant communication problems, the cellular mechanisms responsible for impaired communication are poorly understood. Valproic acid (VPA) is an anticonvulsant that is a known risk factor for autism in prenatally exposed children. Prenatal VPA exposure in rats causes numerous neural and behavioral abnormalities that mimic autism. We predicted that VPA exposure may lead to auditory processing impairments which may contribute to the deficits in communication observed in individuals with autism. In this study, we document auditory cortex responses in rats prenatally exposed to VPA. We recorded local field potentials and multiunit responses to speech sounds in primary auditory cortex, anterior auditory field, ventral auditory field. and posterior auditory field in VPA exposed and control rats. Prenatal VPA exposure severely degrades the precise spatiotemporal patterns evoked by speech sounds in secondary, but not primary auditory cortex. This result parallels findings in humans and suggests that secondary auditory fields may be more sensitive to environmental disturbances and may provide insight into possible mechanisms related to auditory deficits in individuals with autism. © 2014 Wiley Periodicals, Inc. Develop Neurobiol 74: 972–986, 2014 相似文献
6.
Primary auditory cortex (A1) exhibits a tonotopic representation of characteristic frequency (CF). The receptive field properties of A1 neurons emerge from a combination of thalamic inputs and intracortical connections. However, the mechanisms that guide growth of these inputs during development and shape receptive field properties remain largely unknown. We previously showed that Eph family proteins help establish tonotopy in the auditory brainstem. Moreover, other studies have shown that these proteins shape topography in visual and somatosensory cortices. Here, we examined the contribution of Eph proteins to cortical organization of CF, response thresholds and sharpness of frequency tuning. We examined mice with null mutations in EphB2 and EphB3, as these mice show significant changes in auditory brainstem connectivity. We mapped A1 using local field potential recordings in adult EphB2(-/-);EphB3(-/-) and EphB3(-/-) mice, and in a central A1 location inserted a 16-channel probe to measure tone-evoked current-source density (CSD) profiles. Based on the shortest-latency current sink in the middle layers, which reflects putative thalamocortical input, we determined frequency receptive fields and sharpness of tuning (Q(20)) for each recording site. While both mutant mouse lines demonstrated increasing CF values from posterior to anterior A1 similar to wild type mice, we found that the double mutant mice had significantly lower Q(20) values than either EphB3(-/-) mice or wild type mice, indicating broader tuning. In addition, we found that the double mutants had significantly higher CF thresholds and longer onset latency at threshold than mice with wild type EphB2. These results demonstrate that EphB receptors influence auditory cortical responses, and suggest that EphB signaling has multiple functions in auditory system development. 相似文献
7.
Diesch E Preissl H Haerle M Schaller HE Birbaumer N 《Somatosensory & motor research》2001,18(1):10-18
Magnetic source imaging of multiple frequency steady-state somatosensory evoked responses was examined using a 151-channel magnetoencephalography (MEG) system and a dual-channel electrical stimulator. Somatotopy of digit representation was studied in healthy subjects and effects of injury-related cortical plasticity in patients with unilateral transections of the median or the ulnar nerve. Dipole source locations exhibited somatotopic order with overlap between neighboring digits. In two of three nerve injury patients evidence for cortical reorganization was found. The location of sources related to digits neighboring deafferented digits was changed and their dipole moments were enlarged by comparsion with the sources related to contralateral homologue control digits. As a basis for magnetic source imaging, the recording of multiple frequency somatosensory steady-state evoked responses may be a viable and time saving alternative to the recording of transient evoked responses. 相似文献
8.
Eugen Diesch Hubert Preissl Max Haerle Hans-Eberhard Schaller Niels Birbaumer 《Somatosensory & motor research》2013,30(1):10-18
Magnetic source imaging of multiple frequency steady-state somatosensory evoked responses was examined using a 151-channel magnetoencephalography (MEG) system and a dual-channel electrical stimulator. Somatotopy of digit representation was studied in healthy subjects and effects of injury-related cortical plasticity in patients with unilateral transections of the median or the ulnar nerve. Dipole source locations exhibited somatotopic order with overlap between neighboring digits. In two of three nerve injury patients evidence for cortical reorganization was found. The location of sources related to digits neighboring deafferented digits was changed and their dipole moments were enlarged by comparsion with the sources related to contralateral homologue control digits. As a basis for magnetic source imaging, the recording of multiple frequency somatosensory steady-state evoked responses may be a viable and time saving alternative to the recording of transient evoked responses. 相似文献
9.
The auditory cortex of the house mouse: left-right differences, tonotopic organization and quantitative analysis of frequency representation 总被引:3,自引:0,他引:3
I. Stiebler R. Neulist I. Fichtel G. Ehret 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(6):559-571
Multi-unit electrophysiological mapping was used to establish the area of the left- and right-hemisphere auditory cortex
(AC) of the mouse and to characterize various fields within the AC. The AC of the left hemisphere covered a significantly
larger (factor of 1.30) area compared to that of the right side. Based on best-frequency (BF) maps and other neuronal response
characteristics to tone and noise bursts, five fields (primary auditory field, anterior auditory field, second auditory field,
ultrasonic field, dorsoposterior field) and two small non-specified areas could be delimited on both hemispheres. The relative
sizes of these fields and areas were similar on both sides. The primary and anterior auditory fields were tonotopically organized
with counter running frequency gradients merging in the center of the AC. These fields covered BF ranges up to about 45 kHz.
Higher BFs up to about 70 kHz were represented non-tonotopically in the separate ultrasonic field, part of which may be considered
as belonging to the primary field. The dorsoposterior and second auditory fields were non-tonotopically organized and neurons
had special response properties. These characteristics of the mouse AC were compared with auditory cortical maps of other
mammals.
Accepted: 25 July 1997 相似文献
10.
11.
The cochleotopic organization of the primary auditory cortex was studied by the evoked potentials method in cats anesthetized with pentobarbital. Two foci of maximal activity (dorsal and ventral) were found in the primary auditory cortex of 85% of animals during local electrical stimulation of different areas of the cochlea. Analysis of projection maps of the primary auditory cortex of the cats showed that different areas of the cochlea are presented in this region disproportionately. The basal portion projects to a larger cortical surface than the middle and apical portions together, evidence of inequality of representation of different parts of the receptor apparatus of the cochlea in the primary auditory area. Considerable differences were observed in the arrangement of projections of the cochlea in the primary auditory cortex of different animals.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 11, No. 2, pp. 117–124, March–April, 1979. 相似文献
12.
When interfering objects occlude a scene, the visual system restores the occluded information. Similarly, when a sound of interest (a "foreground" sound) is interrupted (occluded) by loud noise, the auditory system restores the occluded information. This process, called auditory induction, can be exploited to create a continuity illusion. When a segment of a foreground sound is deleted and loud noise fills the missing portion, listeners incorrectly report hearing the foreground continuing through the noise. Here we reveal the neurophysiological underpinnings of illusory continuity in single-neuron responses from awake macaque monkeys' primary auditory cortex (A1). A1 neurons represented the missing segment of occluded tonal foregrounds by responding to discontinuous foregrounds interrupted by intense noise as if they were responding to the complete foregrounds. By comparison, simulated peripheral responses represented only the noise and not the occluded foreground. The results reveal that many A1 single-neuron responses closely follow the illusory percept. 相似文献
13.
Frequency resolution and spectral integration (critical band analysis) in single units of the cat primary auditory cortex 总被引:2,自引:0,他引:2
G. Ehret C. E. Schreiner 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,181(6):635-650
Frequency resolution and spectral filtering in the cat primary auditory cortex (AI) were mapped by extracellular recordings
of tone responses in white noise of various bandwidths. Single-tone excitatory tuning curves, critical bandwidths, and critical
ratios were determined as a function of neuronal characteristic frequency and tone level. Single-tone excitatory tuning curves
are inadequate measures of frequency resolution and spectral filtering in the AI, because their shapes (in most neurons) deviated
substantially from the shapes of “tuning curves for complex sound analysis”, the curves determined by the band limits of the
critical bandwidths. Perceptual characteristics of spectral filtering (intensity independence and frequency dependence) were
found in average critical bandwidths of neurons from the central and ventral AI. The highest frequency resolution (smallest
critical bandwidths) reached by neurons in the central and ventral AI equaled the psychophysical frequency resolution. The
dorsal AI is special, since most neurons there had response properties incompatible with psychophysical features of frequency
resolution. Perceptual characteristics of critical ratios were not found in the average neuronal responses in any area of
the AI. It seems that spectral integration in the way proposed to be the basis for the perception of tones in noise is not
present at the level of the AI.
Accepted: 21 July 1997 相似文献
14.
Recent anatomical, physiological, and neuroimaging findings indicate multisensory convergence at early, putatively unisensory stages of cortical processing. The objective of this study was to confirm somatosensory-auditory interaction in A1 and to define both its physiological mechanisms and its consequences for auditory information processing. Laminar current source density and multiunit activity sampled during multielectrode penetrations of primary auditory area A1 in awake macaques revealed clear somatosensory-auditory interactions, with a novel mechanism: somatosensory inputs appear to reset the phase of ongoing neuronal oscillations, so that accompanying auditory inputs arrive during an ideal, high-excitability phase, and produce amplified neuronal responses. In contrast, responses to auditory inputs arriving during the opposing low-excitability phase tend to be suppressed. Our findings underscore the instrumental role of neuronal oscillations in cortical operations. The timing and laminar profile of the multisensory interactions in A1 indicate that nonspecific thalamic systems may play a key role in the effect. 相似文献
15.
16.
Mirror-symmetric tonotopic maps in human primary auditory cortex 总被引:17,自引:0,他引:17
Understanding the functional organization of the human primary auditory cortex (PAC) is an essential step in elucidating the neural mechanisms underlying the perception of sound, including speech and music. Based on invasive research in animals, it is believed that neurons in human PAC that respond selectively with respect to the spectral content of a sound form one or more maps in which neighboring patches on the cortical surface respond to similar frequencies (tonotopic maps). The number and the cortical layout of such tonotopic maps in the human brain, however, remain unknown. Here we use silent, event-related functional magnetic resonance imaging at 7 Tesla and a cortex-based analysis of functional data to delineate with high spatial resolution the detailed topography of two tonotopic maps in two adjacent subdivisions of PAC. These maps share a low-frequency border, are mirror symmetric, and clearly resemble those of presumably homologous fields in the macaque monkey. 相似文献
17.
18.
In order to attain a correct interpretation of an ambiguous visual stimulus, the brain may have to elaborate on the sensory evidence. Are the neurons that carry the sensory evidence also involved in generating an interpretation? To address this question, we studied the activity of neurons in the primary visual cortex of macaque monkeys involved in a task in which they have to trace a curve mentally, without moving their eyes. On a percentage of trials, the monkeys made errors and traced the wrong curve. Here, we show that these errors are predicted by activity in area V1. Thus, neurons in the primary visual cortex do not only represent sensory events, but also the way in which they are interpreted by the monkey. 相似文献
19.
The representation of perceptual space in the posterior parietal cortex can be divided into at least two categories: far space, beyond arm's reach, and peripersonal space, within arm's reach. These are encoded by different groups of neurons that are closely related to the control of gaze and the guidance of arm and hand movement, respectively. 相似文献
20.
R A Andersen 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1997,352(1360):1421-1428
The posterior parietal cortex has long been considered an ''association'' area that combines information from different sensory modalities to form a cognitive representation of space. However, until recently little has been known about the neural mechanisms responsible for this important cognitive process. Recent experiments from the author''s laboratory indicate that visual, somatosensory, auditory and vestibular signals are combined in areas LIP and 7a of the posterior parietal cortex. The integration of these signals can represent the locations of stimuli with respect to the observer and within the environment. Area MSTd combines visual motion signals, similar to those generated during an observer''s movement through the environment, with eye-movement and vestibular signals. This integration appears to play a role in specifying the path on which the observer is moving. All three cortical areas combine different modalities into common spatial frames by using a gain-field mechanism. The spatial representations in areas LIP and 7a appear to be important for specifying the locations of targets for actions such as eye movements or reaching; the spatial representation within area MSTd appears to be important for navigation and the perceptual stability of motion signals. 相似文献